Remote vehicle starting systems are widely used to allow a user to start a vehicle before entering the vehicle, so as to allow the engine of the vehicle to warm up to operating temperatures, for example. A typical remote starting system, for example, includes a central processor or controller connected to a starter circuit for the vehicle engine to cause the starter circuit to start the vehicle engine. A typical remote starting system also includes a receiver associated with the controller that cooperates with one or more remote transmitters typically carried by the user as disclosed, for example, in U.S. Pat. No. 4,383,242 to Sassover et al. and U.S. Pat. No. 5,146,215 to Drori. The remote transmitter may be used to operate the remote start system. Also related to remote control of a vehicle function U.S. Pat. No. 5,252,966 to Lambropoulous et al. discloses a remote keyless entry system for a vehicle. The keyless entry system permits the user to remotely open the vehicle doors or open the vehicle trunk using a small handheld transmitter.
Some remote start systems are connected to other vehicle devices to provide functionality in addition to remote starting. Unfortunately, many prior remote start systems needed to be directly connected by wires to individual vehicle devices. In other words, such a remote start system was hardwired to various vehicle components, typically by splicing into vehicle wiring harnesses or via interposing T-harnesses and connectors. The number of electrical devices in a vehicle has increased so that the size and complexity of wiring harnesses also increased. For example, the steering wheel may include horn switches, an airbag, turn-signal and headlight switches, wiper controls, cruise control switches, ignition wiring, an emergency flasher switch, and/or radio controls. Likewise, a door of a vehicle, for example, may include window controls, locks, outside mirror switches, and/or door-panel light switches.
In response to the increased wiring complexity and costs, vehicle manufacturers have reduced the amount of wiring within vehicles to reduce weight, reduce wire routing problems, decrease costs, and reduce complications which may arise when troubleshooting the electrical system. For example, some manufacturers have adopted multiplexing schemes to reduce cables to three or four wires and to simplify the exchange of data among the various onboard electronic systems as disclosed, for example, in “The Thick and Thin of Car Cabling” by Thompson appearing in the IEEE Spectrum, February 1996, pp. 42-45. The Thompson article describes a number of multiplexed networks for vehicles. In particular, the Grand Cherokee made by Chrysler is described as having five multiplex nodes or controllers: the engine controller, the temperature controller, the airbag controller, the theft alarm, and the overhead console. Other nodes for different vehicles may include a transmission controller, a trip computer, an instrument cluster controller, an antilock braking controller, an active suspension controller, and a body controller for devices in the passenger compartment.
A number of patent references are also directed to digital or multiplex communications networks or circuits, such as may be used in a vehicle. For example, U.S. Pat. No. 4,538,262 Sinniger et al, discloses a multiplex bus system including a master control unit and a plurality of receiver-transmitter units connected thereto. Similarly, U.S. Pat. No. 4,055,772 to Leung discloses a power bus in a vehicle controlled by a low current digitally coded communications system. Other references disclosing various vehicle multiplex control systems include, for example, U.S. Pat. No. 4,760,275 to Sato et al.; U.S. Pat. No. 4,697,092 to Roggendorf et al.; and U.S. Pat. No. 4,792,783 to Burgess et al.
Several standards have been developed for vehicle multiplex networks including, for example, the Society of Automotive Engineers “Surface Vehicle Standard, Class B Data Communications Network Interface”, SAE J1850, July 1995. Another report by the SAE is the “Surface Vehicle Information Report, Chrysler Sensor and Control (CSC) Bus Multiplexing Network for Class ‘A’ Applications”, SAE J2058, July 1990.
Remote starting of the engine presents additional difficulties compared to some other vehicle control applications. This is so because starting the engine may require certain vehicle conditions are correct prior to starting the engine and while the engine is running with the vehicle unattended. It may also be necessary for a remote starter system to bypass an immobilizer device which is part of the security system of some vehicles. For example, U.S. Pat. No. 5,612,578 to Drew entitled “Vehicle Engine Start Control Apparatus Including Interface Device Facilitating Installation and Related Methods” discloses a remote start system which is hardwire connected via mating plugs for more conveniently bypassing an immobilizer circuit based upon a coded resistance of the ignition key.
A significant advance in remote start control of a vehicle is disclosed in U.S. Pat. No. 7,031,826 to Flick, and assigned to the assignee of the present application. The patent discloses integration of remote start functions in a vehicle include a data communications bus extending throughout the vehicle. In aftermarket embodiments, installation of the receiver and associated controller is greatly simplified as compared to equivalent hard-wired systems.
Also relating to remote starting, U.S. Pat. No. 7,031,826 to Flick, discloses determining a transmission position from the data bus, before permitting remote starting. U.S. Pat. No. 8,061,626, also to Flick, discloses a remote climate control system operable over the data bus in a hybrid vehicle including a combination gas/electric power train, or an electric only vehicle. U.S. Pat. No. 7,046,126, also to Flick, discloses a window control system that operates via remote commands received at the vehicle and sent over the data bus within the vehicle.
Despite advances in vehicle remote control, particularly via communication over the vehicle data bus, further advancements in the field are still desirable.